There is a continuing need in various research and industrial arts for polymerizable monomers which can be polymerized into useful copolymers. For example, for photographic elements, there is a need for crosslinking agents to harden gelatin by reaction with the amine groups on the gelatin to covalently bond the crosslinking agent to the gelatin.
Moreover, there is also a continuing need in medical practice and research, and in analytical and diagnostic procedures for rapid and accurate determinations of chemical and biological substances which are present in various fluids, such as biological fluids. For example, the presence of drugs, narcotics, hormones, steroids, polypeptides, metabolites, toxins, viruses, microorganisms or nucleic acids in human or animal body fluids or tissues must be determined rapidly and accurately for effective research, diagnosis or treatment.
In approximately the last twenty years, a wide variety of analytical methods have been developed to detect the substances noted above. Generally, the state of the art has advanced to such a degree that analytical and diagnostic methods have become highly reliable, and suitable for automation or for use with test kits which can be readily used in doctors' offices or at home. Most of such methods rely on what are known in the art as "specific binding" reactions in which an unknown substance to be detected (known as a "ligand") reacts specifically and preferentially with a corresponding "receptor" molecule. Most well known specific binding reactions occur between immunoreactants, such as antibodies and antigens (foreign substances which produce immunological responses).
Methods in the art using the specific binding reactions generally require that one or more of both of the reactants be immobilized on a solid substrate of some type, so that unreacted (and generally water-soluble) materials can then be separated from the water-insoluble reaction product (often called a "complex"). In addition, such immobilized reactants can be used in affinity chromatography to remove a desired biologically active material from a mixture of such materials.
U.S. Pat. No. 4,278,651 (issued Jul. 14, 1981 to Hales) relates to a supported receptor for use in an assay for a ligand in which the solid support contains a water insoluble polymer having available at least one reactive functional group which is either carboxyl, isothiocyanate, N-hydroxysuccinimide, imidazolide, bromoacetyl, maleimide or diazomethylene. The receptor is covalently linked to the support through the reactive functional group. Generally, the support is a core-shell particle having an outer porous coating as the shell which also has the necessary functional groups. The core of the particle provides structural integrity for the porous shell materials.
Acrylic, acid-based photopolymerizable compositions have been prepared which are capable of binding bioactive substances after being photopolymerized, as described in U.S. Pat. No. 4,451,569 (issued May 29, 1984 to Schneider et al). These compositions may be applied as a coating on a carrier substrate, photopolymerized and a bioactive substance fixed thereto. The composition contains acrylic acid, a photoinitiator, a photopolymerization activator and adhesion promoter, and a copolymerizable olefinic monomer which contains a reactive functional group capable of binding bioactive substances. The olefinic monomer is preferably N-hydroxysuccinimide acrylate, N-hydroxysuccinimide amidocaproate, epoxypropyl acrylate or 2-isocyanato-ethyl acrylate.
Also, biologically active substances have thus been immobilized to advantage on particulate substrates such as polymeric particles, animal and human erythrocytes, bacterial cells and other materials known in the art. In some cases, the particulate substrates are fashioned or chemically treated to provide reactive groups on their outer surfaces for appropriate reaction with the biological substance. If the particulate substrate is a polymeric material, it often can be prepared from monomers having the appropriate reactive groups.
For example, carboxylated latex particles have been used to prepare diagnostic reagents, as noted in U.S. Pat. No. 4,181,636 (issued Jan. 1, 1980 to Fischer). The described particles are prepared using a carboxyl-containing monomer such as acrylic acid, methacrylic acid, itaconic acid, aconitic acid, fumaric acid or maleic acid. Similar particles are described in U.S. Pat. No. 3,857,931 (issued Dec. 31, 1974 to Hager), U.S. Pat. No. 4,138,383 (issued Feb. 6, 1979 to Rembaum et al) and U.S. Pat. No. 4,264,766 (issued Apr. 28, 1981 to Fischer).
The reduction of non-specific protein adsorption on polymeric surfaces has been a common goal for many workers trying to apply polymer technology to in vivo and in vitro uses in biotechnology. Undesired non-specific protein adsorption has been a continual problem. For example, nonspecific adsorption is a major concern in the use of polymers for affinity chromatography for the purification of proteins. In assays, non-specific absorption causes unwanted background and obscures true results.
The modification of polymer surfaces has taken many forms, including physical coatings, graft copolymerization, chemical treatments and plasma gas discharge treatment. The hydrophilic nature of the polymer surface has been the subject of considerable debate and research because an increase in hydrophilicity reduces adsorption of some proteins, but not others. As noted in the art cited above, the use of reactive side chains has also received considerable attention in the art.
For example, U.S. Pat. No. 4,710,525 (issued Dec. 1, 1987 to Kraemer) relates to certain polymer particles dispersible to form a latex, to latices of such polymer particles, and to methods for immobilizing (that is, bonding or fixing) a biologically active substance on such particles. These particles have a core-shell construction and comprise groups in the shell region suitable for covalent fixation thereto of a biologically active substance. The shell is also hydrophilic and crosslinked.
Two known monomers, N-acryloyloxysuccinimide and N-(6-methacrylamidohexanoyloxy)succinimide, have been polymerized to form polymers.
Other useful monomers are listed in British Application No. 8035126, published on Jun. 17, 1981, which relates to silver halide photographic materials containing a reactive polymer having a pendant active ester group. This application lists monomers having an active ester group which can be polymerized by known methods to form the photographic materials to which this application is directed. The polymers also have the capability of being used as a crosslinked latex.
Notwithstanding the current state of the art in medical practice and analytical and diagnostic procedures, there is a need in the industry for the novel non-crosslinked copolymers of this invention which comprise water-insoluble, non-porous particles. The copolymers of this invention have the advantages of not being swellable in water so that the activity of the "receptor", as described previously, is not compromised. Further advantages of the copolymers of this invention are that: 1) it extends away from bead surface for ready covalent attachment, 2) it does not hydrolyze before covalent attachment, 3) it reacts readily and completely to form covalent protein bonds, 4) it has good reactivity with styrene monomers, and 5) the reaction chemistry is mild and does not produce by-products that require clean-up.
There is a need in the art to find new polymers which show improvement over the standard succinimideoxycarbonyl-containing polymers, especially in the attachment of biological materials for use in research and various analytical and diagnostic procedures, and also in other arts such as photography.
More recently, however, succinimidoxycarbonyl compounds have been used for this purpose with considerable advantages, as described in related application, U.S. Ser. No. 646,303 (of Sutton, et al) previously referred to herein.